Device for detecting the occupied state and the free state of a track section as well as method for operating such a device

ABSTRACT

An apparatus for the detection of an occupied or free state of a track section, which is particularly simple and at the same time particularly resistant to interference influences, includes a transmitter for feeding a transmitted signal, encoded by modulation, into rails of the track section and at least one receiver for receiving a received signal which is brought about by transmission of the transmitted signal through the running rails of the track section. The apparatus compares the modulation of the received signal with the modulation of the transmitted signal. A method for operation of an apparatus for detection of the occupied and free state of a track section is also provided.

The present invention relates to an apparatus for detection of the occupied or free state of a track section having a transmitter for feeding a transmitted signal which is coded by means of modulation, into the rails of the track section and at least one receiver for receiving a received signal which is produced by transmission of the transmitted signal via the rails of the track section.

One such apparatus is known in the form of a track free signaling device, in the form of a track circuit, for example from the company publication from Siemens AG “FTG S—Gleisfreimeldung mit dem Tonfrequenz-Gleisstromkreis FTG S” [FTG S—Track free signaling using the FTG S audio-frequency track circuit], Order No. A19100-V100-B607-V2. In this case, the transmitter feeds an AC voltage into the rails of a track section to be monitored. A receiver receives a received signal in the form of the incoming voltage, and evaluates the received signal. Since a short circuit is produced between the rails of the track section by the axles of a rail vehicle which is traveling on the track section, this prevents the transmitted signal from being transmitted to the receiver. This therefore makes it possible to identify that the relevant track section is occupied.

In order to improve the reliability against disturbance influences and in particular to make the track circuit insensitive to electrical influences caused by harmonics in the track return current, the transmitted signal is coded by means of modulation in the known apparatus.

In this case, one of a total of 15 available, fixed predetermined bit patterns of different length for each track circuit frequency is modulated as coding onto the transmitted signal. At the receiver end, the coding is read in the form of the modulation from the received signal and is compared with the fixed predetermined coding for the respective track circuit. This ensures an unambiguous and correct association such that a received signal received by the receiver also actually originated from the transmitter for the same track circuit. This precludes the possibility of a received signal from a different track circuit incorrectly being received, for example because of electrical influences, for instance by the conductors in two lines which are carried in one cable touching, and being used for the detection of the occupied or free state of the track section.

The known apparatus has the disadvantage that only 15 bit patterns are available for coding. When using an audio-frequency track circuit with transmitted signals at a different frequency, it is in this case frequently not possible to preclude or avoid multiple use of transmitted signals both at the same frequency and with the same bit pattern within one project or one system, as a result of which increased disturbance loads can occur.

The present invention is based on the object of specifying a particularly simple apparatus of the type mentioned initially which is particularly insensitive to disturbance influences at the same time.

According to the invention, this object is achieved by an apparatus for detection of the occupied or free state of a track section having a transmitter for feeding a transmitted signal which is coded by means of modulation, into the rails of the track section and at least one receiver for receiving a received signal which is produced by transmission of the transmitted signal via the rails of the track section, wherein the apparatus is designed to compare the modulation on the received signal with the modulation on the transmitted signal.

Therefore, the invention is distinguished in that a solution which is completely detached from the known concept is provided, in that a receiver receives a received signal which is coded by means of modulation and checks the modulation on the received signal by comparison with modulation which is known at the receiver end and is predetermined to be fixed for the relevant apparatus. Instead of this, the corresponding check is carried out according to the invention in that the apparatus is designed to compare the modulation on the received signal with the modulation on the transmitted signal. The association between the two signals is therefore verified in a particularly simple manner by comparison of the modulations on the received signal and on the transmitted signal. This advantageously avoids the need to use rigid, fixed predetermined codings, for example in the form of bit patterns, and to permanently associate corresponding codings with the respective apparatus. This advantageously also avoids corresponding effects for configuration of the individual apparatuses, thus reducing the production costs of the apparatus. Furthermore, the fitting process is also simplified, thus additionally resulting in a time and therefore cost saving. In addition, the configuration of a railroad monitoring system is also simplified, since there is no need to provide associations between codings or modulations and apparatuses, and there is therefore also no need to store corresponding associations on location plans and data sheets and to subsequently take account of these. Furthermore, there are advantageously also no restrictions relating to the number and the nature of the modulations used for coding, thus creating the precondition for making it possible to preclude multiple use of the same modulations within one system.

It should be noted that, for the purposes of the apparatus according to the invention, the transmitted signal is preferably an audio-frequency signal. Furthermore, however, it is likewise possible to use a transmitted signal at a frequency of below or above the audio frequency range, or else in the form of a direct-current signal.

The apparatus is preferably designed such that, when the modulation on the received signal is compared with the modulation on the transmitted signal, any discrepancy between the modulations is found, and the track section associated with that apparatus is immediately signaled as being occupied, in order to avoid danger.

According to one particularly preferred embodiment, the apparatus according to the invention is designed to produce a transmitted signal (SIG_(S)) which is coded by means of any desired modulation, in particular random-number based. This is advantageous because the use of any desired modulation, in particular random-number based, as coding makes it possible to virtually preclude any influence between two apparatuses in a monitoring system resulting from the use of the same modulation. In this case, any desired modulation may be used, because there is no fixed association between the coding used and the respect apparatus or the respective transmitter, and the way in which the coding is produced ensures that it is possible to preclude with confidence verging on certainty that two apparatuses would use the same modulation within one system. Appropriate algorithms by means of which random-number based coding of the respective transmitted signal can be carried out, for example using random numbers or else pseudo-random numbers are known per se from mathematics and information technology, as a result of which these will not be described in any more detail in the following text. It should be noted that the use of any desired modulation, which is also in particular random-number based or is generated on the basis of random numbers, is made possible for the first time by the apparatus according to the invention allowing comparison of the modulation and therefore checking of the association between the transmitted signal and the received signal without the receiver needing to known in advance the modulation used for coding the transmitted signal.

According to a further particularly preferred embodiment, the apparatus according to the invention is designed to produce a transmitted signal which is coded by means of frequency modulation. This is advantageous because known apparatuses for detection of the occupied or free state of a track section, for example in the form of track circuits, frequently already use transmitted signals which are coded by means of frequency modulation. This is because frequency modulation is particularly insensitive to disturbance influences during transmission. However, in addition to the use of frequency modulation, it is in principle also possible to code the transmitted signal by means of amplitude modulation or phase modulation.

The apparatus according to the invention is preferably also distinguished in that it is designed to produce a transmitted signal which is coded by means of modulation in the form of a bit sequence. For the purposes of this preferred development of the apparatus according to the invention, the transmitted signal is therefore coded by means of digital modulation in the form of a bit sequence. This is advantageous because appropriate digital modulation is particularly robust and insensitive to disturbance influences. In this case, the bit sequence can preferably have any desired length, that is to say, in particular, it is also possible for the bit sequence to have an infinite length, as a result of which it is generated continuously and is random because of the way in which it is generated, as a result of which there is no fixed bit pattern in the form that a part of the bit sequence is regularly repeated.

In principle, the modulation on the received signal can be compared in any desired manner with the modulation on the transmitted signal. If the apparatus is designed to produce a transmitted signal which is coded by means of modulation in the form of a bit sequence, the apparatus according to the invention can advantageously be designed such that it is designed for bit-by-bit comparison of the modulation on the received signal with the modulation on the transmitted signal. Particularly in the comparison for use of codings with fixed, rigid bit patterns, a bit-by-bit comparison of the modulation on the received signal with the modulation on the transmitted signal is advantageous, because a comparison such as this can be carried out very quickly. Furthermore, and in contrast to the known procedure, the recovery time after a disturbance event in which a transmitted bit is destroyed is short, because there is no need for synchronization and evaluation of bit patterns of predetermined length. Finally, therefore, the availability of the apparatus is improved because of the continuous information evaluation by the bit-by-bit comparison.

According to a further particularly preferred development, the apparatus according to the invention is designed for continuous coding of the transmitted signal. This means that the transmitted signal is coded continuously and permanently. This is advantageous because the correct association between the transmitter and the receiver, that is to say the reception of the received signal resulting from the transmitter in the apparatus, can be verified and therefore ensured at any time on the basis of the comparison of the modulation on the received signal with the modulation on the transmitted signal. As an alternative to continuous coding or modulation of the transmitted signal, it is, however, also feasible, depending on the respective circumstances and conditions, for the transmitted signal to be coded only at times. On the one hand, by way of example, this could be done by the transmitted signal being coded with the modulation only at regular recurring times, that is to say for example every 10 seconds. Furthermore, in principle, an appropriate modulation could also be carried out only in the course of a preferably regular functional test of the apparatus.

According to one particularly preferred development of the apparatus according to the invention, the apparatus is designed to compare, in a manner which is safe from the signaling point of view, the modulation on the received signal with the modulation on the transmitted signal. This is advantageous because this reliably precludes and avoids corruptions or errors in the course of the comparison of the modulations. This is therefore of major importance, in particular for all safety-critical apparatuses for detection of the occupied or free state of a track section.

As already mentioned above, if, during the comparison of the modulation on the received signal with the modulation on the transmitted signal, the evaluation device finds a discrepancy between the modulations, the apparatus indicates an occupied state for the relevant track section. Furthermore, the apparatus according to the invention can advantageously be distinguished in that it is designed to produce a fault signal, which indicates a disturbance state, based on the comparison of the modulation on the received signal with the modulation on the transmitted signal. The fault signal makes it possible to identify the existing disturbance immediately and quickly and to overcome this as quickly as possible, on this basis.

In principle, the fault signal which is produced may be output in any desired manner. According to a further particularly preferred embodiment, the apparatus according to the invention is designed to output the fault signal in the form of a visual and/or audible warning signal. This is advantageous because this makes it possible to alert an operator, for example in a signal box, of the existing disturbance particularly quickly and reliably.

The apparatus according to the invention can also furthermore be designed such that the apparatus is designed to transmit data signals via the rails of the track section to a rail vehicle which is occupying the track section. This is advantageous because the apparatus according to the invention can therefore additionally be used in a manner known per se to transmit data signals to a rail vehicle. This means that the apparatus according to the invention can additionally be used for track-free signaling, and, for example, for line train control.

Furthermore, the present invention relates to a method for operation of an apparatus for detection of the occupied or free state of a track section, wherein a transmitted signal, which is coded by means of modulation, is fed into the rails of the track section, and a received signal which results from transmission of the transmitted signal via the rails of the track section is received.

With regard to the method, the present invention is based on the object of specifying a particularly simple method, which is at the same time particularly insensitive to disturbances, of the type mentioned above.

According to the invention, this object is achieved by a method for the operation of an apparatus for detection of the occupied or free state of a track section, wherein a transmitted signal, which is coded by means of modulation, is fed into the rails of the track section, and a received signal which results from the transmission of the transmitted signal via the rails of the track section is received, and the modulation on the received signal is compared with the modulation on the transmitted signal.

The advantages of the method according to the invention correspond to those of the apparatus according to the invention, as a result of which reference is made in this context to the corresponding statements above. This also applies to the preferred developments of the method according to the invention mentioned in the following text, in respect of the corresponding preferred developments of a apparatus according to the invention, as a result of which reference is likewise made in this context to the corresponding statements above.

The method according to the invention can preferably be carried out such that the transmitted signal is coded by means of any desired modulation, in particular random-number based.

According to a further particularly preferred embodiment of the method according to the invention, the transmitted signal is coded by means of frequency modulation.

Advantageously, the method according to the invention can also be distinguished in that the transmitted signal is coded by means of modulation in the form of a bit sequence.

The method according to the invention can preferably also be carried out in that the modulation on the received signal is compared bit-by-bit with the modulation on the transmitted signal.

According to a further particularly preferred development of the method according to the invention, the transmitted signal is coded continuously.

According to one particularly preferred embodiment, the method according to the invention is carried out such that the modulation on the received signal is compared, in a manner which is safe from the signaling point of view, with the modulation on the transmitted signal.

According to a further particularly preferred embodiment of the method according to the invention, a fault signal which indicates a disturbance state is produced on the basis of the comparison of the modulation on the received signal with the modulation on the transmitted signal.

According to a further particularly preferred refinement of the method according to the invention, the fault signal is output in the form of a visual and/or audible warning signal.

Preferably, the method according to the invention can also be developed such that data signals are transmitted via the rails of the track section to a rail vehicle which is occupying the track section.

The invention will be explained in more detail in the following text with reference to one exemplary embodiment. For this purpose, and in order to explain one exemplary embodiment of the method according to the invention,

The FIGURE shows a schematic sketch of an arrangement having one track section, as well as one exemplary embodiment of the apparatus according to the invention.

The FIGURE illustrates an apparatus V for detection of the occupied or free state of a track section G. The apparatus V has a transmitter S for feeding a transmitted signal SIG_(S) in the form of an AC voltage into the rails F of the track section G. Furthermore the apparatus V has a receiver E for receiving a received signal SIG_(E) which is produced by transmission of the transmitted signal via the rails F of the track section G.

As shown in the illustration in the FIGURE, an AC voltage at the frequency f1 is fed into the track section G. In order to make it possible to reliably distinguish between the respective signals, the adjacent track sections are operated with an AC voltage at a different frequency f5 or f3. The following text assumes that the arrangement illustrated in the FIGURE is an audio-frequency track circuit having a plurality of frequencies, in which an AC voltage in the form of a transmitted signal SIG_(S) in the audio-frequency range is fed into rails F of the track section G.

By way of example, the apparatus V may be arranged in a signal box of a railway system, or a railway monitoring system. This offers the advantage that particularly high reliability is achieved since mechanical loading and climatic influences have less influence on the electronic components in the apparatus V than would be the case if these components were accommodated in the vicinity of the track. Furthermore, this results in further advantages with respect to availability and maintenance of the apparatus V, that is to say in particular of the transmitter S and of the receiver E. The horizontal dashed-dotted line in the FIGURE indicates corresponding separation between the internal system, which is associated with the apparatus V, and the external system, which is associated with the track section G.

As shown in the illustration in the FIGURE, track connecting housings GAG1, GAG2 are arranged on the trackside and are used to introduce the transmitted signal SIG_(S), which is fed in and provided by the transmitter S, and to read out the received signal SIG_(E), which is transmitted to the receiver E, respectively into and out of the rails F. In this case, the track connecting housings GAG1, GAG2 normally do not contain any active electronic components, but essentially only a resonant circuit for frequency-selective amplification of the signals fed in and fed out at a predetermined useful frequency, that is to say the frequency f1 of the transmitted signal SIG_(S) and of the received signal SIG_(E) in the case of the track section G illustrated in the FIGURE.

The transmitted signal SIG_(S) from the transmitter S is coded by means of modulation. Appropriate codings are used in order to improve the reliability in the event of disturbance influences, that is to say for example to reduce the probability of an appropriated coded transmitted signal SIG_(S) being simulated by disturbance amplitudes. In this case, corresponding disturbances can be caused on the one hand by external sources, but on the other hand also by other apparatuses V, that is to say for example by track circuits arranged in the vicinity.

In the case of track circuits known from the prior art, a fixed predetermined, rigid coding is normally modulated on at the transmitter end, is transmitted, and the coding is read out at the receiver end and compared with the fixed predetermined coding associated with the respective track circuit. Because of the use of rigid bit patterns, multiple use of the same bit pattern cannot be completely precluded, even when the same signal frequency is used. This increases the disturbance load on the track circuits. Furthermore, the recovery time after a disturbance event with bit destruction is comparatively long because of the synchronization required with regard to the fixed bit pattern and the evaluation of bit sequences of predetermined length required for this purpose. In practice, this leads to a further restriction to the availability of the apparatus.

In the exemplary embodiment as shown in the FIGURE, the disadvantages mentioned above are avoided in that the apparatus V is designed to compare the modulation on the received signal SIG_(E) with the modulation on the transmitted signal SIG_(S). This makes it possible to verify that the received signal SIG_(E) received by the receiver E has also actually been produced by the transmitted signal SIG_(S) fed by the transmitter S.

The comparison of the received signal SIG_(E) with the transmitted signal SIG_(S) advantageously makes it possible to produce a transmitted signal SIG_(S) which is coded by means of any desired modulation, in particular random-number based, and to feed this into the rails F of the track section G. The transmitted signal SIG_(S) is preferably a transmitted signal coded by means of frequency modulation, with the apparatus V preferably generating a continuous “bit sequence stream”, randomly. This bit sequence stream is modulated onto the transmitted signal SIG_(S) and, after being transmitted via the rails F of the track section G, is read out at the receiver end by means of the received signal SIG_(E).

According to the exemplary embodiment in the FIGURE, the apparatus V also has an evaluation device AE, in addition to the transmitter S and the receiver E. The evaluation device AE is used on the one hand to produce the bit sequence stream, that is to say the coding in the form of the continuous bit sequence. The evaluation device AE transmits the bit sequence that is produced to the transmitter S, which transmits the transmitted signal SIG_(S), which is coded by means of the modulation in the form of the bit sequence, in order to be fed into the rails F of the track section G. On the other hand, the evaluation device AE also receives from the receiver E the received signal SIG_(E) and the coding, determined from the received signal SIG_(E), in the form of the corresponding frequency modulation. This makes it possible for the evaluation device AE to carry out a bit-by-bit comparison of the modulation on the received signal SIG_(E), with the modulation on the transmitted signal SIG_(S). In this case, bit-by-bit comparison offers the advantage that this can be carried out quickly. The evaluation device AE is preferably designed to compare, in a manner which is safe from the signaling point of view, the modulation on the received signal SIG_(E) with the modulation on the transmitted signal SIG_(S). The signaling certainty of the evaluation device AE can in this case be ensured by architecture measures which are known in their own right and are required in order to achieve the safety level normally required in the field of railroad technology. By way of example, corresponding measures may comprise the evaluation device making use of two channels throughout and the use of safe computers.

In accordance with the above statements, there is advantageously no need for rigid bit patterns, defined in advance, for the purposes of the apparatus according to the invention and the method according to the invention. Particularly as a result of the transmitted signal being coded by means of any desired modulation, in particular a random-number based, this makes it possible to virtually preclude any influence between two apparatuses, that is to say for example track circuits, resulting from the same codings or bit information.

Overall, therefore, the present invention results in considerable advantages with respect to reducing the disturbance arising within a project or a system. Furthermore, the continuous information evaluation, that is to say the bit-by-bit comparison, improves the availability of the apparatus V, without any need for complex synchronizations depending on the length of a rigid bit pattern that is used, for example in the event of bit destruction.

Furthermore, there is advantageously no need to set a bit pattern which is in each case permanently associated with the respective track section G and the respective apparatus V of the track section G by appropriate setting-up or configuration, for example by using so-called bit pattern plugs, at the transmitter end and receiver end. This reduces the number of components required for the apparatus V, and saves time for assembly of the apparatus V. Furthermore, the setting-up process is also simplified because there is no need to associate bit patterns with track circuits in location plans and data sheets. Furthermore, the use of the method according to the invention and the apparatus according to the invention makes it possible to virtually completely dispense with restrictions relating to a line and cable routing, since thorough reliable checking is possible to determine whether a received signal SIG_(E) received by the receiver E actually relates to the relevant track section G. The only exception in this case is that the lines of the transmitter S and of the associated receiver E for the same track section G and the same apparatus V should still be routed separately from one another, in order to prevent coupling or crosstalk of the transmitted signal SIG_(S) into the line of the receiver E. Corresponding to the above statements, one important reason that the restrictions relating to cable routing can be dispensed with is that identical bit sequences for different apparatuses V can be virtually precluded, in particular even in the case in which the bit sequence for coding of the transmitted signal SIG_(S) is generated on a random-number basis.

In summary, it can therefore be stated that the embodiment of the apparatus V according to the invention as shown in the FIGURE allows an increase in the disturbance insensitivity of the apparatus V for detection of the occupied or free state of the track section G and at the same time achieving a simplification and, associated with this, a cost reduction. 

1-20. (canceled)
 21. An apparatus for detection of an occupied or free state of a track section having rails, the apparatus comprising: a transmitter for feeding a transmitted signal, coded by modulation, into the rails of the track section; and at least one receiver for receiving a received signal produced by transmission of the transmitted signal through the rails of the track section; the apparatus being configured to compare the modulation on the received signal with the modulation on the transmitted signal.
 22. The apparatus according to claim 21, wherein the apparatus is configured to produce the transmitted signal coded by any desired modulation.
 23. The apparatus according to claim 21, wherein the apparatus is configured to produce the transmitted signal coded by random-number based modulation.
 24. The apparatus according to claim 21, wherein the apparatus is configured to produce the transmitted signal coded by frequency modulation.
 25. The apparatus according to claim 21, wherein the apparatus is configured to produce the transmitted signal coded by bit sequence modulation.
 26. The apparatus according to claim 25, wherein the apparatus is configured for bit-by-bit comparison of the modulation on the received signal with the modulation on the transmitted signal.
 27. The apparatus according to claim 21, wherein the apparatus is configured for continuous coding of the transmitted signal.
 28. The apparatus according to claim 21, wherein the apparatus is configured to compare, in a manner being safe from a signaling point of view, the modulation on the received signal with the modulation on the transmitted signal.
 29. The apparatus according to claim 21, wherein the apparatus is configured to produce a fault signal indicating a disturbance state, based on the comparison of the modulation on the received signal with the modulation on the transmitted signal.
 30. The apparatus according to claim 29, wherein the apparatus is configured to output the fault signal as at least one of a visual or audible warning signal.
 31. The apparatus according to claim 21, wherein the apparatus is configured to transmit data signals through the rails of the track section to a rail vehicle occupying the track section.
 32. A method for operation of an apparatus for detection of an occupied or free state of a track section having rails, the method comprising the following steps: feeding a transmitted signal, coded by modulation, into the rails of the track section; receiving a received signal resulting from transmission of the transmitted signal through the rails of the track section; and comparing the modulation on the received signal with the modulation on the transmitted signal.
 33. The method according to claim 32, which further comprises coding the transmitted signal by any desired modulation.
 34. The method according to claim 32, which further comprises coding the transmitted signal by random-number based modulation.
 35. The method according to claim 32, which further comprises coding the transmitted signal by frequency modulation.
 36. The method according to claim 32, which further comprises coding the transmitted signal by bit sequence modulation.
 37. The method according to claim 36, which further comprises comparing the modulation on the received signal bit-by-bit with the modulation on the transmitted signal.
 38. The method according to claim 32, which further comprises coding the transmitted signal continuously.
 39. The method according to claim 32, which further comprises comparing the modulation on the received signal, in a manner being safe from a signaling point of view, with the modulation on the transmitted signal.
 40. The method according to claim 32, which further comprises producing a fault signal indicating a disturbance state, based on the comparison of the modulation on the received signal with the modulation on the transmitted signal.
 41. The method according to claim 40, which further comprises outputting the fault signal as at least one of a visual or audible warning signal.
 42. The method according to claim 32, which further comprises transmitting data signals through the rails of the track section to a rail vehicle occupying the track section. 